My WAN IP address is different from my ISP Address. I have two DVR at home, I can see them inside my house, but not from outside.
We may need some more information regarding ip’s. To pass the public IP to out device, you will need to set the ISP router to bridged mode. Then you will need to figure out what ports your DVR is using and create the applicable portforwards to it or just create a NAT Mapping.
Are you on an cellular connection?